1. Technical Field
Several aspects of the present invention relate to an optical element as well as to a projection display device.
2. Related Art
Wire-grid polarizers are known as one of the optical elements provided with a polarization separation function. These wire-grid polarizers have multiple conductive fine wires arranged at a pitch shorter than the wavelength of light, and they reflect an incident light component that has a polarization axis parallel to the fine wires, while transmitting another component that has a polarization axis orthogonal to the fine wires.
Wire-grid polarizers are formed of an inorganic substance and therefore excel in light resistance. For this reason, there are attempts to apply these wire-grid polarizers to projection display devices such as projectors which require to polarize and separate high luminance light (refer to JP-A-2002-372749). FIG. 22 is a schematic drawing illustrating an example of a configuration of a projection display device using two wire-grid polarizers 5. As shown in this drawing, a liquid crystal device 10 is interposed between the two wire-grid polarizers 5, and light is incident to the liquid crystal device 10 from one of the wire-grid polarizers 5. This incident light is converted to display light by the polarization separation function of the wire-grid polarizers 5 at both the entry and exit side, as well as by the polarization conversion function of the liquid crystal device 10. The display light is then projected to a screen 61 through a projection lens 51.
In the above structure, however, the specular reflection of the light by one of the wire-grid polarizers 5 arranged on the exit side of the liquid crystal device 10 occurs. Therefore, the reflected intense light irradiates part of the liquid crystal device 10. This results in problems of the reduced lifetime or unstable operation of the liquid crystal device 10.